STUDY OF ROCK MAGNETISM AND GEOCHEMISTRY IN SEDIMENTS OF LAMPENISU AND MAHALONA RIVERS, TOWUTI DISTRICT, EAST LUWU, SOUTH SULAWESI

• Main Author: - NIM: 22316006 , WAHIDAH
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/31524
• Institution: Institut Teknologi Bandung

<p align="justify">Lake Towuti is a very interesting lake to be a research object with the aim of reconstructing the ancient climate and environment. This is because such lake is situated in the Indo Pacific Warm Pool (IPWP) surrounded by vast ocean areas of warm temperatures with high rainfall rates that accelerate weathering and sedimentation processes. Sediments entering Lake Towuti have large variations in terms of mineral content as they pass through rocks along the river. The sediments deposited in Lake Towuti are rich in Mg especially those which are deposited in the northern part. These minerals were originally thought to be originated from Mahalona Lake through the Mahalona River. However, doubt still rises because there is a branching of Lampenisu River in the Mahalona River. Based on topographic conditions, Lampenisu River has the potential to become the dominant source of sediment entering Lake Towuti. To be able to know it, the magnetic and geochemical characterization were done using surface sediment which was taken in 12 along Lampenisu River (LR), Mahalona River (MR) and the joining the two rivers (LMR). The XRD and VSM measurements show that the dominant magnetic minerals in those three zones are magnetite with PSD. However, the three zones vary based on their value of susceptibility and chemical composition. The magnetic susceptibility value in Lampenisu River (&#967;lf average = 525,983 x 10-8 m3kg-1) is higher than the Mahalona River (&#967;lf average = 218,283 x 10-8 m3kg-1), while the magnetic susceptibility of the meeting point between the two rivers has a moderate value (&#967;lf average = 262.958 x 10-8 m3kg-1). The variation in values is also shown in the &#967;fd. Mahalona River has a higher &#967;fd value than Lampenisu River. Furthermore, geochemical measurements using XRF and REE analysis also show that the sediment characteristics of the Lampenisu and Mahalona Rivers are very different. The mineral that goes to Lake Towuti is the result of contribution from both rivers. It also reinforces that magnetic mineral resources in northern part of Lake Towuti not only come from the sediments of the Mahalona River but there is also a major contribution of the Lampenisu River sediment. The Mg which was originally thought to be derived from the Mahalona River turns out to have a larger amount in the Lampenisu River. <p align="justify">